Fuel consumption indicator



July 16,1940.

P. Of SKLDBERG FUEL CONSUMPTION INDICATOR Filed Oct. 27, 1958 2SheelLs-SheeI l fw @fof seaczmfg- MMM wvl alu-"urn up! f Patented July16, 1940 uNlTEo sTATEs PATENT OFFICE Per Oloi.' Sl'xldberg, Stockholm,Sweden.

Application October 27, 1938, Serial No. 237,323 v In Sweden November 9,1937 1 Claim.-

engine is in operation. A further object of the invention is to providean apparatus for the pur.- pose indicated, which is of simpleconstruction and readily applicable to existing engines and which.directly indicates the fuel consumption in, for instance, gallons permile or miles per gallon.

attain these objects by mechanism illustrated in the accompanyingdrawings, in which: Fig. 1 is a vertical section of4 the apparatus; Fig.2 shows, to a larger scale, a detail of the novel apparatus;

Fig. 3 is a section taken on the line 3-3 of Fig. 2; y

Fig. 4 is a diagram illustrating certain pressures in relation to theposition of the throttle valve of the carburetor; and

Fig. 5 is another embodiment of the invention. Referring rs't to Fig. 1,I have illustrated a carburetor of a well-known type, generally denotedby C and including gasoline inlet Ill, iioat chamber II, iioat I2, floatvalve I3, compound 35.1noz`zle I4, idling nozzle I5, air intake I6,choke tube I1, and throttle I8. The carburetor itself forms no part ofthe invention and may be of any desired type. I9 indicates the inletpipe for the mixture of gasoline vapor and air, said pipe 40 beingconnected to the intake manifold (not' illustrated) of the engine.

A pipe is connected to the choke tube Il by means of a nipple 2| screwedthrough the wall of the pipe 22 and secured in proper posi- 45 tion by anut 23. A pipe 24 is connected to the inlet pipe I9 at-a place behindthe throttle I8,

'umn of mercury indicatedin millimetres.

the drawing, the nipple 425 can easily beadjusted so that the axis ofthe aperture 29 will form any desired angle a with the direction of flowof the combustion gases through the inlet pipe I9,

said direction being substantially parallel to the longitudinal axis 3I.Nipple 25 is provided with a hexagonal portion 34 by which the nipplemay be turned to vary the direction of axis 30..

The' pipes M'and 2t are connected to a diierential gauge 32 including ascale 33 and a pointer 3d 'and adapted to indicate the diiierencebetween the pressure prevailing before the throttle i8 and the pressurebehind the throttle. The gauge 32" is conveniently placed on' theinstrument panel. As will be seen from the following consideration inconnection with the diagram shown in Fig. 4, any pressure differenceindicated by the gauge t2 corresponds approximately to a certain fuelconsumption per revolution of the engine. n

In Fig. 4, the abscissae of the coordinate system represent the positionoi the throttle I8 and the ordinates thereof represent pressure incoll-/I indicates the position in which the throttle is full open,whereas' at O. the throttle entirely closes the intake to the engine.

The curves 'p1 and p1 indicate the static pressure prevailing before thethrottle i8, and the curves p2 and p2' indicate the static pressurebehind the throttle, both at two diierent b'ut constant speedsv of theengine, n and n', respectively, the speed n' being higher than n. lf theengine speed is assumed to be constant, the position of the throttle isa measure of the load on v the engine.

the throttle position B where b=p1-pz'=a. If

Q and Q', respectively, denote the corresponding quantities of fueliiowing to the engine per unit of time, the fuel consumption perrevolution Vwill counted in the direction of flow of the combusbe tiongases. A nipple or joint 25, which is secured in its positionby the nut26 and connected to the pipe 24 by the nut 21, has a central passage QQQ It follows therefrom that the pressure dierence pi-pz indicated bythe differential gauge 32 is l a measure of the fuelcons'umption perrevolution and consequently also per unit of -length of the road onwhich a motor car or the like runs, proactly to the real fuelconsumption. In the embodiment shown, such compensation is obtained.

by varying the angle a between the direction of ow of the combustiongases and the longitudinal axis of the aperture 2Q. The less thelanglea, the greater will be the pressure acting on the gauge due to thekinetic energy of the mixture. In this way, the aperture 29 can beadjusted, and the gauge calibrated, such as exactly to indicate theconsumption oi fuel, for instance in gallons per mile or miles pergallon, which consumption canA be directly ascertained on the gauge.

In case of motor cars, the pipe 24 can be connected to the intake tubeI9 at the place where the pipe, through which the vacuum windshieldwiper is actuated, is connected to the tube i9, whereby the provision ofa special aperture in the wall of the tube i 9 is avoided.

While the embodiment ci the invention described above is constructed inaccordance with theoretical considerations, I have found that the sameresults can be obtained by means of a same type as that illustrated inFig. 1. Il is a vacuum gauge which by means of a pipevu'` is connectedto the inlet pipe Il' at a' place behindthe throttle i8. The connectbnbetween the pipes 24' and I l' is eiiected by a nipple 2B' provided withan aperture 29' the position of whichI canbe varied in the-same mann'erand for the same purpose as described in conjunction with the aperture29 of the embodiment shown in Figs. 1 vto 3. In a certain position ofthe aperture 29', which position must be ascertained experimentally, thegauge can be calibrated so that it directly indicates the fuelconsumption. What I claim is: g Y An instrument for indicating the fuelconsumption .of an internal combustion engine having a carburetor and athrottle valve between the carburetor and the inlet pipe of the engine,said instrument including a pressure gauge, atubular member forconnecting said gauge with the inlet pipe, said tubular member having arotatable adjustable portion extending into the inlet pipe and providedwith an aperture adapted to be PER omr' sKLpBEaG.

